1. Field of the Invention
The present invention relates generally to an apparatus and method for slitting metal material, and particularly to an apparatus and method for slitting aluminum.
A particular application of the present invention lies in the transformer windings field, and the problem addressed and solved by the present invention relates to the slitting associated with the fabrication of aluminum strip material into narrow strips for use as transformer windings.
2. Prior Art
In many transformers aluminum strips approximately three inches in width are used as windings with a paper, resin or other insulating material interleaving between the windings. One of the difficulties encountered in cutting or slitting the aluminum strips into the required width is the burring which occurs due to the normal slitting process. The resulting burrs have an adverse effect on the transformer life as they punch the interleaving, causing the transformer to arc and, thus, shorten its life. The problem, then, is to eliminate the burring associated with slitting of the aluminum strip.
While there are devices known in the art for slitting metal material, such as disclosed in U.S. Pat. Nos. 3,416,347; 3,641,853: 3,656,379; 3,762,249: 4,109,500; and Re 27,658, we are not familiar with any device which specifically addresses the problem noted above. The U.S. Pat. No. 3,416,347 is the most significant of the group cited in terms of the stated problem. According to this patent a coiled strip material is passed through a single-knife slitting unit where the material is vertically scored along transversely spaced lines on the top and bottom thereof, then passed through a separating unit and ultimately to an edge conditioning unit where the edges of the severed strips are smoothed and rounded. The single-edge knife system taught by the patent inherently produces burred edges, requiring further edge conditioning. Smoothing and rounding the edges of severed strips is required to eliminate this burring and the resultant likelihood of puncturing the transformer interleaving. What is undesirable, however, is the requirement for a separate unit to produce this edge effect.
There is therefore a need for effectively eliminating the noted burring in a less complicated manner, i.e., with fewer elements.